1. Field of the Invention
This invention relates to a dictionary data registration apparatus and dictionary data registration method used in a walker authentication apparatus that authenticates a walker by, for example, photographing a face image of a to-be-authenticated person who is walking and collating face data of the to-be-authenticated person (walker) photographed with face data previously registered as dictionary data.
2. Description of the Related Art
In most of the conventional general face authentication apparatuses, an authentication process for a to-be-authenticated person is performed by photographing the face image of the to-be-authenticated person who stands still and collating the photographed face image with previously registered face images. On the other hand, recently, a walker authentication apparatus that authenticates a walker by photographing a face image of the walker and collating face data of the photographed walker with face data previously registered as dictionary data is developed. In the above walker authentication apparatus, an image containing a face of a person who is walking is photographed by a camera, a face region of the walker is extracted from the photographed image and face data (input subspace) as a feature amount of the face obtained from the image (face image) of the extracted face region is collated with face data (registered subspace) previously registered as dictionary data.
In the above walker authentication apparatus, since the face of a person who is walking is photographed, a variation in the state of the face image in the photographed image is large. For example, since a to-be-authenticated person is walking, the posture of the to-be-authenticated person (the direction of the face) varies to a larger extent in comparison with a case wherein he stands still. Further, since the camera is not used to photograph only a person in a specified position, a variation in the photographing conditions becomes large due to a variation in the environment, such as the position of the to-be-photographed person or illumination. Generally, in a face collation process, the collation precision is degraded if the posture of the face image (face direction) photographed at the time of the collation process and the posture of the face image (face direction) photographed at the registration time vary or the photographing conditions at the collation process time and at the registration time vary. Therefore, in the walker authentication apparatus, it is necessary to frequently update registration information (face image for registration) or acquire a plurality of registration information items in various conditions in order to stably attain authentication performance.
For example, in order to collect face images containing variations in postures while he is actually walking, it is considered to collect a lot of face images of a registrant while walking by causing the registrant to repeatedly walk along a passage. Further, in order to collect face images containing variations in an environment, it is necessary to require that the registrant repeatedly walk along the passage while the environment is varied. However, with the above method, it is necessary to force the registrant to repeatedly walk along the passage. Therefore, the above collection method of face images for registration imposes a heavy load on the user and is not very practical.
Further, conventionally, there is provided a method for urging the registrant to vary the posture (face direction) according to guidance and collecting and registering face images photographed in required postures as face images for registration (for example, Jpn. Pat. Appln. KOKAI Publication No. 2003-141541). In the above registration method, various face images can be collected by varying desired postures. However, since a variation in the posture while he actually walks is not reflected, there occurs a possibility that the collation precision may be lowered and a variation will occur in the collation precision.
As described above, in the conventional walker authentication apparatus, there occurs a problem that a load placed on the user will increase and a load on management will become heavier due to frequent updating of dictionary data in order to collect registration information (face images for registration) in a dictionary data registration process.